Based on the primary hypothesis that prevalence of the Factor V Leiden mutation will be higher in patients with vein graft occlusions than in those without, this pilot study seeks to estimate the prevalence of the mutation in 100 patients w/ 100 patients without angiographically proven vein graft occlusion. The presence of the mutation is strongly associated w/ deep venous but not arterial thrombotic events. If the association can be established with greater risk of veingraft failure, an argument could be made to avoid vein grafts in pts w/ the mutation.